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Question 1
Incorrect
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A 38-year-old woman who had a kidney transplant 3 years ago visits the transplant clinic for follow-up. She has been in good health and is currently on tacrolimus medication to prevent transplant rejection.
What is the mode of action of tacrolimus?Your Answer: Purine metabolism antagonist
Correct Answer: Calcineurin inhibitor
Explanation:Tacrolimus functions as a calcineurin inhibitor, which is a type of immunosuppressant used to prevent transplant rejection. Alkylating agents like cyclophosphamide and platinum compounds are also used for immunosuppression in autoimmune diseases. Methotrexate, a folic acid analogue, inhibits the synthesis of tetrahydrofolate to exhibit its immunosuppressive action. Azathioprine and similar medications work by antagonizing purine metabolism to maintain immunosuppression after a transplant.
Tacrolimus: An Immunosuppressant for Transplant Rejection Prevention
Tacrolimus is an immunosuppressant drug that is commonly used to prevent transplant rejection. It belongs to the calcineurin inhibitor class of drugs and has a similar action to ciclosporin. The drug works by reducing the clonal proliferation of T cells by decreasing the release of IL-2. It binds to FKBP, forming a complex that inhibits calcineurin, a phosphatase that activates various transcription factors in T cells. This is different from ciclosporin, which binds to cyclophilin instead of FKBP.
Compared to ciclosporin, tacrolimus is more potent, resulting in a lower incidence of organ rejection. However, it is also associated with a higher risk of nephrotoxicity and impaired glucose tolerance. Despite these potential side effects, tacrolimus remains an important drug in preventing transplant rejection and improving the success of organ transplantation.
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This question is part of the following fields:
- General Principles
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Question 2
Incorrect
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A known opiate-abuser in his mid-twenties is observed injecting a substance and subsequently collapsing on the street. He is immediately transported to the emergency department. What acid-base disturbance would be anticipated in this scenario?
Your Answer: Metabolic acidosis
Correct Answer: Respiratory acidosis
Explanation:Opiate Injection and Respiratory Acidosis
When a person injects opiates, it can lead to respiratory depression. This means that the person’s breathing will slow down, causing an increase in carbon dioxide (CO2) levels in the body. As a result, the person may experience respiratory acidosis, which is a condition where the blood becomes too acidic due to the buildup of CO2. This can lead to symptoms such as confusion, drowsiness, and shortness of breath. It is important to seek medical attention immediately if someone is experiencing these symptoms after injecting opiates. Proper treatment can help prevent further complications and ensure a safe recovery.
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This question is part of the following fields:
- Clinical Sciences
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Question 3
Incorrect
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An 80-year-old man has been referred to the respiratory clinic due to a persistent dry cough and hoarse voice for the last 5 months. He reports feeling like he has lost some weight as his clothes feel loose. Although he has no significant past medical history, he has a 30-pack-year smoking history. During the examination, left-sided miosis and ptosis are noted. What is the probable location of the lung lesion?
Your Answer: Lung periphery
Correct Answer: Lung apex
Explanation:The patient’s persistent cough, significant smoking history, and weight loss are red flag symptoms of lung cancer. Additionally, the hoarseness of voice suggests that the recurrent laryngeal nerve is being suppressed, likely due to a Pancoast tumor located in the apex of the lung. The presence of Horner’s syndrome further supports this diagnosis. Mesothelioma, which is more common in patients with a history of asbestos exposure, typically presents with shortness of breath, chest wall pain, and finger clubbing. A hamartoma, a benign tumor made up of tissue such as cartilage, connective tissue, and fat, is unlikely given the patient’s red flags for malignant disease. Small cell carcinomas, typically found in the center of the lungs, may present with a perihilar mass and paraneoplastic syndromes due to ectopic hormone secretion. Lung cancers within the bronchi can obstruct airways and cause respiratory symptoms such as cough and shortness of breath, but not hoarseness.
Lung Cancer Symptoms and Complications
Lung cancer is a serious condition that can cause a range of symptoms and complications. Some of the most common symptoms include a persistent cough, haemoptysis (coughing up blood), dyspnoea (shortness of breath), chest pain, weight loss and anorexia, and hoarseness. In some cases, patients may also experience supraclavicular lymphadenopathy or persistent cervical lymphadenopathy, as well as clubbing and a fixed, monophonic wheeze.
In addition to these symptoms, lung cancer can also cause a range of paraneoplastic features. These may include the secretion of ADH, ACTH, or parathyroid hormone-related protein (PTH-rp), which can cause hypercalcaemia, hypertension, hyperglycaemia, hypokalaemia, alkalosis, muscle weakness, and other complications. Other paraneoplastic features may include Lambert-Eaton syndrome, hypertrophic pulmonary osteoarthropathy (HPOA), hyperthyroidism due to ectopic TSH, and gynaecomastia.
Complications of lung cancer may include hoarseness, stridor, and superior vena cava syndrome. Patients may also experience a thrombocytosis, which can be detected through blood tests. Overall, it is important to be aware of the symptoms and complications of lung cancer in order to seek prompt medical attention and receive appropriate treatment.
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This question is part of the following fields:
- Respiratory System
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Question 4
Incorrect
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A 28-year-old patient arrives at the emergency department with a fever, neck stiffness, photophobia, and a non-blanching rash. Despite being vaccinated, they are experiencing these symptoms. During a lumbar puncture, the fluid obtained is turbid, with low glucose and an elevated opening pressure. What is the probable causative organism responsible for this patient's condition?
Your Answer: Haemophilus influenzae B
Correct Answer: Streptococcus pneumoniae
Explanation:The most common cause of meningitis in adults is Streptococcus pneumoniae, which is also the likely pathogen in this patient’s case. His symptoms and lumbar puncture results suggest bacterial meningitis, with turbid fluid, raised opening pressure, and low glucose. While Escherichia coli is a common cause of meningitis in infants under 3 months, it is less likely in a 29-year-old. Haemophilus influenzae B is also an unlikely cause in this patient, who is up-to-date with their vaccinations and beyond the age range for this pathogen. Staphylococcus pneumoniae is a rare but serious cause of pneumonia, but not as likely as Streptococcus pneumoniae to be the cause of this patient’s symptoms.
Aetiology of Meningitis in Adults
Meningitis is a condition that can be caused by various infectious agents such as bacteria, viruses, and fungi. However, this article will focus on bacterial meningitis. The most common bacteria that cause meningitis in adults is Streptococcus pneumoniae, which can develop after an episode of otitis media. Another bacterium that can cause meningitis is Neisseria meningitidis. Listeria monocytogenes is more common in immunocompromised patients and the elderly. Lastly, Haemophilus influenzae type b is also a known cause of meningitis in adults. It is important to identify the causative agent of meningitis to provide appropriate treatment and prevent complications.
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This question is part of the following fields:
- Neurological System
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Question 5
Correct
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Olivia is a 19-year-old female who has recently started college. She attends a party and has many alcoholic drinks and wakes the next morning with a severe headache. She puts this down to being hungover, however, by the next day the headache is worse and she has a widespread non-blanching purpuric rash. She attends the emergency department who suspect meningitis and would like to perform a lumbar puncture to obtain a cerebrospinal fluid (CSF) sample. The doctor would like to take the sample from the cauda equina to avoid spinal cord injury, at which level does the spinal cord terminate?
Your Answer: L1/L2
Explanation:CSF Analysis for Meningitis
Cerebrospinal fluid (CSF) analysis is an important diagnostic tool for meningitis. The appearance, glucose level, protein level, and white cell count in the CSF can provide clues to the type of meningitis present. Bacterial meningitis typically results in cloudy CSF with low glucose levels and high protein levels, along with a high number of polymorphs. Viral meningitis, on the other hand, usually results in clear or slightly cloudy CSF with normal or slightly raised protein levels and a high number of lymphocytes. Tuberculous meningitis may result in slightly cloudy CSF with a fibrin web and a high number of lymphocytes, along with low glucose and high protein levels. Fungal meningitis typically results in cloudy CSF with high protein levels and a high number of lymphocytes. In cases of suspected tuberculous meningitis, PCR may be used in addition to the Ziehl-Neelsen stain, which has low sensitivity. It is important to note that mumps and herpes encephalitis may also result in low glucose levels in the CSF.
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This question is part of the following fields:
- General Principles
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Question 6
Correct
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A 45-year-old obese woman presents to the Emergency Department complaining of sudden lower back pain. Upon conducting a neurological examination, you observe a decrease in the left knee jerk reflex compared to the right. Which spinal level does this correspond to?
Your Answer: L3-L4
Explanation:Memory aid for common reflexes:
S1-S2, buckle my shoe (ankle)
L3-L4, kick the door (knee)
C5-C6, pick up sticks (biceps)
C7-C8, shut the gate (triceps)The reflex tested by tapping the knee is the L3-L4 reflex.
Reflexes are automatic responses that our body makes in response to certain stimuli. These responses are controlled by the nervous system and do not require conscious thought. There are several common reflexes that are associated with specific roots in the spinal cord. For example, the ankle reflex is associated with the S1-S2 root, while the knee reflex is associated with the L3-L4 root. Similarly, the biceps reflex is associated with the C5-C6 root, and the triceps reflex is associated with the C7-C8 root. Understanding these reflexes can help healthcare professionals diagnose and treat certain conditions.
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This question is part of the following fields:
- Neurological System
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Question 7
Correct
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A 72-year-old patient presents to the Emergency Room with central crushing chest pain that radiates to their jaw and left arm. They have a medical history of hypertension, type 2 diabetes mellitus, and hypercholesterolemia. The patient receives percutaneous coronary intervention but unfortunately experiences ventricular fibrillation and passes away 3 days later. What is the probable histological discovery in their heart?
Your Answer: Extensive coagulative necrosis, neutrophils
Explanation:Myocardial infarction (MI) can lead to various complications, which can occur immediately, early, or late after the event. Cardiac arrest is the most common cause of death following MI, usually due to ventricular fibrillation. Cardiogenic shock may occur if a large part of the ventricular myocardium is damaged, and it is difficult to treat. Chronic heart failure may result from ventricular myocardium dysfunction, which can be managed with loop diuretics, ACE-inhibitors, and beta-blockers. Tachyarrhythmias, such as ventricular fibrillation and ventricular tachycardia, are common complications. Bradyarrhythmias, such as atrioventricular block, are more common following inferior MI. Pericarditis is common in the first 48 hours after a transmural MI, while Dressler’s syndrome may occur 2-6 weeks later. Left ventricular aneurysm and free wall rupture, ventricular septal defect, and acute mitral regurgitation are other complications that may require urgent medical attention.
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This question is part of the following fields:
- Cardiovascular System
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Question 8
Incorrect
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A 27-year-old Afro-Caribbean woman visits her GP with concerns about well-defined patches of significantly lighter skin. At first, this was only on her hands, but she has recently noticed similar patches on her face. She has a medical history of Hashimoto's thyroid disease and takes levothyroxine.
During the examination, the GP observes well-demarcated areas of hypopigmentation on her hands, arms, and face. Based on the most probable diagnosis, which layer of the epidermis is affected?Your Answer: Stratum granulosum
Correct Answer: Stratum germinativum
Explanation:The deepest layer of the epidermis is called the stratum germinativum, which is responsible for producing keratinocytes and contains melanocytes. Vitiligo, a condition characterized by depigmented patches, affects this layer by causing the loss of melanocytes.
The stratum corneum is the topmost layer of the epidermis, consisting of dead cells filled with keratin.
The stratum granulosum is where keratin production occurs in the epidermis.
The stratum lucidum is only present in the palms of the hands and soles of the feet.
The Layers of the Epidermis
The epidermis is the outermost layer of the skin and is made up of a stratified squamous epithelium with a basal lamina underneath. It can be divided into five layers, each with its own unique characteristics. The first layer is the stratum corneum, which is made up of flat, dead, scale-like cells filled with keratin. These cells are continually shed and replaced with new ones. The second layer, the stratum lucidum, is only present in thick skin and is a clear layer. The third layer, the stratum granulosum, is where cells form links with their neighbors. The fourth layer, the stratum spinosum, is the thickest layer of the epidermis and is where squamous cells begin keratin synthesis. Finally, the fifth layer is the stratum germinativum, which is the basement membrane and is made up of a single layer of columnar epithelial cells. This layer gives rise to keratinocytes and contains melanocytes. Understanding the layers of the epidermis is important for understanding the structure and function of the skin.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 9
Incorrect
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Which of the following medications used in the treatment of hyperlipidemia is most likely to cause flushing?
Your Answer: Ezetimibe
Correct Answer: Nicotinic acid
Explanation:Side-effects of drugs used in hyperlipidaemia
Hyperlipidaemia is a condition characterized by high levels of lipids in the blood. Drugs used to treat this condition have different mechanisms of action and can cause various adverse effects. Statins, which are HMG CoA reductase inhibitors, work by reducing the production of cholesterol in the liver. However, they can cause myositis (muscle inflammation) and deranged liver function tests (LFTs). Ezetimibe, on the other hand, decreases cholesterol absorption in the small intestine, but it can cause headaches. Nicotinic acid decreases hepatic VLDL secretion, but it can cause flushing and myositis. Fibrates, which are agonists of PPAR-alpha and increase lipoprotein lipase expression, can cause myositis, pruritus, and cholestasis. Cholestyramine decreases bile acid reabsorption in the small intestine, upregulating the amount of cholesterol that is converted to bile acid, but it can cause gastrointestinal side-effects. It is important to weigh the benefits and risks of each drug when choosing a treatment for hyperlipidaemia.
Overall, the table above summarizes the different mechanisms of action and adverse effects of drugs used in hyperlipidaemia. It is important to note that each drug has its own set of benefits and risks, and patients should discuss their options with their healthcare provider to determine the best course of treatment. Proper monitoring and management of adverse effects can help ensure the safety and effectiveness of these medications.
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This question is part of the following fields:
- General Principles
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Question 10
Correct
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A 16-year-old male is suspected to have testicular torsion and requires scrotal exploration surgery. After making an incision in the skin and dartos muscle, what is the next layer of tissue that the surgeon will encounter during dissection?
Your Answer: External spermatic fascia
Explanation:The layers that will be encountered in the given scenario are as follows, in sequential order:
1. The skin layer
2. The dartos fascia and muscle layer
3. The external spermatic fascia layer
4. The cremasteric muscle and fascia layer
5. (Unknown or unspecified layer)Anatomy of the Scrotum and Testes
The scrotum is composed of skin and dartos fascia, with an arterial supply from the anterior and posterior scrotal arteries. It is also the site of lymphatic drainage to the inguinal lymph nodes. The testes are surrounded by the tunica vaginalis, a closed peritoneal sac, with the parietal layer adjacent to the internal spermatic fascia. The testicular arteries arise from the aorta, just below the renal arteries, and the pampiniform plexus drains into the testicular veins. The left testicular vein drains into the left renal vein, while the right testicular vein drains into the inferior vena cava. Lymphatic drainage occurs to the para-aortic nodes.
The spermatic cord is formed by the vas deferens and is covered by the internal spermatic fascia, cremasteric fascia, and external spermatic fascia. The cord contains the vas deferens, testicular artery, artery of vas deferens, cremasteric artery, pampiniform plexus, sympathetic nerve fibers, genital branch of the genitofemoral nerve, and lymphatic vessels. The vas deferens transmits sperm and accessory gland secretions, while the testicular artery supplies the testis and epididymis. The cremasteric artery arises from the inferior epigastric artery, and the pampiniform plexus is a venous plexus that drains into the right or left testicular vein. The sympathetic nerve fibers lie on the arteries, while the parasympathetic fibers lie on the vas. The genital branch of the genitofemoral nerve supplies the cremaster. Lymphatic vessels drain to lumbar and para-aortic nodes.
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This question is part of the following fields:
- Reproductive System
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Question 11
Correct
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A 35-year-old man with a history of ulcerative colitis is commencing treatment with 6-mercaptopurine following a recurrence of his symptoms.
What is the mechanism of action of this medication?Your Answer: Decreases purine synthesis
Explanation:Ulcerative colitis, a type of inflammatory bowel disease characterized by bloody diarrhea, can be treated with various medications such as sulfasalazine, infliximab, 6-mercaptopurine, and in severe cases, a colectomy. 6-mercaptopurine is a purine analogue that is activated by HGPRTase, leading to decreased purine synthesis and reduced DNA synthesis. It is commonly used to treat non-malignant conditions like systemic lupus erythematosus, rheumatoid arthritis, and inflammatory bowel disease. On the other hand, 5-fluorouracil is a pyrimidine analogue that acts as an antimetabolite, interfering with DNA synthesis, and is used to treat colorectal and pancreatic cancer. Methotrexate, an antimetabolite that acts as a folic acid analogue, is widely used in many malignancies and non-malignant conditions such as rheumatoid arthritis, psoriasis, and inflammatory bowel disease. Bleomycin, doxorubicin, and daunorubicin cause free radical formation, leading to breaks in the DNA strand, while busulfan is an alkylating agent that causes cross-links in the DNA and is typically used to ablate a patient’s bone marrow before a bone marrow transplant.
Cytotoxic agents are drugs that are used to kill cancer cells. There are several types of cytotoxic agents, each with their own mechanism of action and potential adverse effects. Alkylating agents, such as cyclophosphamide, work by causing cross-linking in DNA. However, they can also cause haemorrhagic cystitis, myelosuppression, and transitional cell carcinoma. Cytotoxic antibiotics, like bleomycin and anthracyclines, degrade preformed DNA and stabilize DNA-topoisomerase II complex, respectively. However, they can also cause lung fibrosis and cardiomyopathy. Antimetabolites, such as methotrexate and fluorouracil, inhibit dihydrofolate reductase and thymidylate synthesis, respectively. However, they can also cause myelosuppression, mucositis, and liver or lung fibrosis. Drugs that act on microtubules, like vincristine and docetaxel, inhibit the formation of microtubules and prevent microtubule depolymerisation & disassembly, respectively. However, they can also cause peripheral neuropathy, myelosuppression, and paralytic ileus. Topoisomerase inhibitors, like irinotecan, inhibit topoisomerase I, which prevents relaxation of supercoiled DNA. However, they can also cause myelosuppression. Other cytotoxic drugs, such as cisplatin and hydroxyurea, cause cross-linking in DNA and inhibit ribonucleotide reductase, respectively. However, they can also cause ototoxicity, peripheral neuropathy, hypomagnesaemia, and myelosuppression.
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This question is part of the following fields:
- Haematology And Oncology
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Question 12
Incorrect
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A 48-year-old male visits his GP with blister-like skin alterations that have been bothering him for a few months on his body and inside his mouth. Upon biopsy, it is revealed that there are intra-epithelial blisters containing acantholytic keratinocytes.
What skin condition is known to present with these features?Your Answer: Actinic keratosis
Correct Answer: Pemphigus vulgaris
Explanation:Pemphigus vulgaris is likely the condition that a middle-aged man with acantholytic keratinocytes and involvement of the mouth (mucous membranes) would present with. This is because this condition is characterised by intra-epithelial blisters containing acantholytic keratinocytes.
Bullous pemphigoid, on the other hand, is characterised by damage to the hemidesmosomes and infiltration of white blood cells such as lymphocytes into the affected area. It does not demonstrate acantholytic keratinocytes and does not affect mucous membranes like the mouth.
Actinic keratosis does not cause blistering, and bullous impetigo typically affects babies.
Pemphigus vulgaris is an autoimmune condition that occurs when the body’s immune system attacks desmoglein 3, a type of cell adhesion molecule found in epithelial cells. This disease is more prevalent in the Ashkenazi Jewish population. The most common symptom is mucosal ulceration, which can be the first sign of the disease. Oral involvement is seen in 50-70% of patients. Skin blistering is also a common symptom, with easily ruptured vesicles and bullae. These lesions are typically painful but not itchy and may appear months after the initial mucosal symptoms. Nikolsky’s sign is a characteristic feature of pemphigus vulgaris, where bullae spread following the application of horizontal, tangential pressure to the skin. Biopsy results often show acantholysis.
The first-line treatment for pemphigus vulgaris is steroids, which help to reduce inflammation and suppress the immune system. Immunosuppressants may also be used to manage the disease.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 13
Incorrect
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A 56-year-old man presents to the emergency department with profuse haematemesis. Upon admission, his vital signs include a temperature of 36.9ºC, oxygen saturation of 94% on air, heart rate of 124 beats per minute, respiratory rate of 26 breaths per minute, and blood pressure of 82/58 mmHg. An urgent endoscopy was performed to achieve haemostasis, revealing an ulcer on the posterior wall of the duodenum. Which artery is the most likely source of the gastrointestinal bleed?
Your Answer: Inferior pancreaticoduodenal artery
Correct Answer: Gastroduodenal artery
Explanation:Duodenal ulcers on the posterior wall pose a risk to the gastroduodenal artery, which supplies blood to this area. The posterior wall is a common site for duodenal ulcers, and erosion of the ulcer through the duodenal wall can result in severe upper gastrointestinal bleeding. The inferior mesenteric artery, on the other hand, supplies blood to the hindgut (transverse colon, descending colon, and sigmoid colon) and does not include the duodenum. The inferior pancreaticoduodenal artery, which arises from the superior mesenteric artery, supplies the lower part of the duodenum but does not provide the majority of the blood supply to the posterior duodenal wall, which is mainly supplied by the gastroduodenal artery.
Acute upper gastrointestinal bleeding is a common and significant medical issue that can be caused by various conditions, with oesophageal varices and peptic ulcer disease being the most common. The main symptoms include haematemesis (vomiting of blood), melena (passage of altered blood per rectum), and a raised urea level due to the protein meal of the blood. The diagnosis can be determined by identifying the specific features associated with a particular condition, such as stigmata of chronic liver disease for oesophageal varices or abdominal pain for peptic ulcer disease.
The differential diagnosis for acute upper gastrointestinal bleeding includes oesophageal, gastric, and duodenal causes. Oesophageal varices may present with a large volume of fresh blood, while gastric ulcers may cause low volume bleeds that present as iron deficiency anaemia. Duodenal ulcers are usually posteriorly sited and may erode the gastroduodenal artery. Aorto-enteric fistula is a rare but important cause of major haemorrhage associated with high mortality in patients with previous abdominal aortic aneurysm surgery.
The management of acute upper gastrointestinal bleeding involves risk assessment using the Glasgow-Blatchford score, which helps clinicians decide whether patients can be managed as outpatients or not. Resuscitation involves ABC, wide-bore intravenous access, and platelet transfusion if actively bleeding platelet count is less than 50 x 10*9/litre. Endoscopy should be offered immediately after resuscitation in patients with a severe bleed, and all patients should have endoscopy within 24 hours. Treatment options include repeat endoscopy, interventional radiology, and surgery for non-variceal bleeding, while terlipressin and prophylactic antibiotics should be given to patients with variceal bleeding. Band ligation should be used for oesophageal varices, and injections of N-butyl-2-cyanoacrylate for patients with gastric varices. Transjugular intrahepatic portosystemic shunts (TIPS) should be offered if bleeding from varices is not controlled with the above measures.
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This question is part of the following fields:
- Gastrointestinal System
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Question 14
Incorrect
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Which statement about the standard error of the mean is accurate?
Your Answer: Is the square root of standard deviation
Correct Answer: Gets smaller as the sample size increases
Explanation:Understanding Confidence Interval and Standard Error of the Mean
The confidence interval is a widely used concept in medical statistics, but it can be confusing to understand. In simple terms, it is a range of values that is likely to contain the true effect of an intervention. The likelihood of the true effect lying within the confidence interval is determined by the confidence level, which is the specified probability of including the true value of the variable. For instance, a 95% confidence interval means that the range of values should contain the true effect of intervention 95% of the time.
To calculate the confidence interval, we use the standard error of the mean (SEM), which measures the spread expected for the mean of the observations. The SEM is calculated by dividing the standard deviation (SD) by the square root of the sample size (n). As the sample size increases, the SEM gets smaller, indicating a more accurate sample mean from the true population mean.
A 95% confidence interval is calculated by subtracting and adding 1.96 times the SEM from the mean value. However, if the sample size is small (n < 100), a 'Student's T critical value' look-up table should be used instead of 1.96. Similarly, if a different confidence level is required, such as 90%, the value used in the formula should be adjusted accordingly. In summary, the confidence interval is a range of values that is likely to contain the true effect of an intervention, and its calculation involves using the standard error of the mean. Understanding these concepts is crucial in interpreting statistical results in medical research.
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This question is part of the following fields:
- General Principles
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Question 15
Correct
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A 70-year-old man suffers a right neck of femur fracture following a fall at home. The following blood test results are obtained:
- Calcium: 1.80 mmol/L (normal range: 2.25 - 2.50)
- Phosphate: 0.6 mmol/L (normal range: 0.80 - 1.50)
- PTH: 14.0 pmol/L (normal range: 1.6 - 6.9)
- Vitamin D: 15 nmol/L (normal range: >50)
The patient is given medication to address the underlying cause of his condition.
What is the primary mechanism by which the active metabolite of this medication increases serum calcium levels?Your Answer: Increased absorption of calcium from the small intestine
Explanation:Vitamin D increases serum calcium primarily by increasing its absorption from the small intestine. This patient has secondary hyperparathyroidism due to vitamin D deficiency, which leads to low serum calcium and phosphate levels. PTH levels increase in response to low calcium levels. Vitamin D supplementation is required to treat the underlying cause. Vitamin D increases serum calcium through increased absorption from the small intestine, increased reabsorption by the kidneys, and increased bone resorption, but the effect on the small intestine is the most significant. Increased PTH secretion, increased bone resorption, and increased reabsorption by the kidneys are incorrect mechanisms.
Understanding Vitamin D
Vitamin D is a type of vitamin that is soluble in fat and is essential for the metabolism of calcium and phosphate in the body. It is converted into calcifediol in the liver and then into calcitriol, which is the active form of vitamin D, in the kidneys. Vitamin D can be obtained from two sources: vitamin D2, which is found in plants, and vitamin D3, which is present in dairy products and can also be synthesized by the skin when exposed to sunlight.
The primary function of vitamin D is to increase the levels of calcium and phosphate in the blood. It achieves this by increasing the absorption of calcium in the gut and the reabsorption of calcium in the kidneys. Vitamin D also stimulates osteoclastic activity, which is essential for bone growth and remodeling. Additionally, it increases the reabsorption of phosphate in the kidneys.
A deficiency in vitamin D can lead to two conditions: rickets in children and osteomalacia in adults. Rickets is characterized by soft and weak bones, while osteomalacia is a condition where the bones become weak and brittle. Therefore, it is crucial to ensure that the body receives an adequate amount of vitamin D to maintain healthy bones and overall health.
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This question is part of the following fields:
- General Principles
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Question 16
Incorrect
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Which of the following is not a branch of the abdominal aorta?
Your Answer: Renal artery
Correct Answer: Superior phrenic artery
Explanation:To remember the order of branches, use the phrase ‘Prostitutes Cause Sagging Swollen Red Testicles [in men] Living In Sin’:
Phrenic [inferior]
Celiac
Superior mesenteric
Suprarenal [middle]
Renal
Testicular [‘in men’ only]
Lumbars
Inferior mesenteric
SacralNote that the superior phrenic artery branches from the aorta in the thorax.
Branches of the Abdominal Aorta
The abdominal aorta is a major blood vessel that supplies oxygenated blood to the abdominal organs and lower extremities. It gives rise to several branches that supply blood to various organs and tissues. These branches can be classified into two types: parietal and visceral.
The parietal branches supply blood to the walls of the abdominal cavity, while the visceral branches supply blood to the abdominal organs. The branches of the abdominal aorta include the inferior phrenic, coeliac, superior mesenteric, middle suprarenal, renal, gonadal, lumbar, inferior mesenteric, median sacral, and common iliac arteries.
The inferior phrenic artery arises from the upper border of the abdominal aorta and supplies blood to the diaphragm. The coeliac artery supplies blood to the liver, stomach, spleen, and pancreas. The superior mesenteric artery supplies blood to the small intestine, cecum, and ascending colon. The middle suprarenal artery supplies blood to the adrenal gland. The renal arteries supply blood to the kidneys. The gonadal arteries supply blood to the testes or ovaries. The lumbar arteries supply blood to the muscles and skin of the back. The inferior mesenteric artery supplies blood to the descending colon, sigmoid colon, and rectum. The median sacral artery supplies blood to the sacrum and coccyx. The common iliac arteries are the terminal branches of the abdominal aorta and supply blood to the pelvis and lower extremities.
Understanding the branches of the abdominal aorta is important for diagnosing and treating various medical conditions that affect the abdominal organs and lower extremities.
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This question is part of the following fields:
- Gastrointestinal System
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Question 17
Incorrect
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A 50-year-old male is brought back to a surgical ward after a renal transplant. Diuresis suddenly decreases 2 hours after the transplantation. The patient is quickly transferred back to surgery where the transplanted kidney displays signs of hyperacute rejection and is removed. Histopathological examination confirms hyperacute rejection.
What type of reaction has this patient undergone?Your Answer: Type I hypersensitivity
Correct Answer: Type II hypersensitivity
Explanation:Hyperacute transplant rejection is a type II hypersensitivity reaction, which is characterized by a cytotoxic response caused by pre-existing antibodies to the ABO or HLA antigens. This reaction leads to widespread thrombosis and ischaemia/necrosis within the transplanted organ, necessitating its surgical removal.
In contrast, type I hypersensitivity is an immediate IgE-mediated reaction that occurs within minutes, while type III hypersensitivity is an IgM-mediated reaction that involves the formation of circulating immune complexes. Type IV hypersensitivity is a cell-mediated response that takes weeks to develop and is seen in chronic graft rejections. Finally, type V hypersensitivity is an autoimmune reaction that involves the binding of auto-antibodies to cell surface receptors, either preventing the intended ligand binding or mimicking its effects.
The HLA system, also known as the major histocompatibility complex (MHC), is located on chromosome 6 and is responsible for human leucocyte antigens. Class 1 antigens include A, B, and C, while class 2 antigens include DP, DQ, and DR. When matching for a renal transplant, the importance of HLA antigens is ranked as DR > B > A.
Graft survival rates for renal transplants are high, with a 90% survival rate at one year and a 60% survival rate at ten years for cadaveric transplants. Living-donor transplants have even higher survival rates, with a 95% survival rate at one year and a 70% survival rate at ten years. However, postoperative problems can occur, such as acute tubular necrosis of the graft, vascular thrombosis, urine leakage, and urinary tract infections.
Hyperacute rejection can occur within minutes to hours after a transplant and is caused by pre-existing antibodies against ABO or HLA antigens. This type of rejection is an example of a type II hypersensitivity reaction and leads to widespread thrombosis of graft vessels, resulting in ischemia and necrosis of the transplanted organ. Unfortunately, there is no treatment available for hyperacute rejection, and the graft must be removed.
Acute graft failure, which occurs within six months of a transplant, is usually due to mismatched HLA and is caused by cell-mediated cytotoxic T cells. This type of failure is usually asymptomatic and is detected by a rising creatinine, pyuria, and proteinuria. Other causes of acute graft failure include cytomegalovirus infection, but it may be reversible with steroids and immunosuppressants.
Chronic graft failure, which occurs after six months of a transplant, is caused by both antibody and cell-mediated mechanisms that lead to fibrosis of the transplanted kidney, known as chronic allograft nephropathy. The recurrence of the original renal disease, such as MCGN, IgA, or FSGS, can also cause chronic graft failure.
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This question is part of the following fields:
- Renal System
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Question 18
Correct
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A 50-year-old man with type 2 diabetes mellitus visits his GP for his annual health check-up. His HbA1c level is 86mmol/L and the GP is contemplating the addition of empagliflozin to his diabetes management plan.
What is the mechanism of action of empagliflozin?Your Answer: Inhibition of the sodium-glucose transporter in the kidney
Explanation:SGLT-2 inhibitors work by blocking the action of sodium-glucose co-transporter 2 (SGLT-2) in the renal proximal convoluted tubule, which leads to a decrease in glucose re-absorption into the circulation. Empagliflozin is an example of an SGLT-2 inhibitor.
Sulphonylureas increase insulin secretion from β islet cells in the pancreas by blocking potassium channels, which causes islet cell depolarisation and release of insulin.
DPP-4 inhibitors, such as sitagliptin, prevent the breakdown of GLP-1 (glucagon-like peptide) by inhibiting the enzyme DPP-4. This leads to suppression of glucagon release and an increase in insulin release.
Acarbose inhibits α glucosidase and other enzymes in the small intestine, which prevents the breakdown of complex carbohydrates into glucose. This results in less glucose being available for absorption into the bloodstream.
Thiazolidinediones reduce insulin resistance in peripheral tissues and decrease gluconeogenesis in the liver by stimulating PPAR-γ (peroxisome proliferator-activated receptor-gamma), which modulates the transcription of genes involved in glucose metabolism.
Understanding SGLT-2 Inhibitors
SGLT-2 inhibitors are medications that work by blocking the reabsorption of glucose in the kidneys, leading to increased excretion of glucose in the urine. This mechanism of action helps to lower blood sugar levels in patients with type 2 diabetes mellitus. Examples of SGLT-2 inhibitors include canagliflozin, dapagliflozin, and empagliflozin.
However, it is important to note that SGLT-2 inhibitors can also have adverse effects. Patients taking these medications may be at increased risk for urinary and genital infections due to the increased glucose in the urine. Fournier’s gangrene, a rare but serious bacterial infection of the genital area, has also been reported. Additionally, there is a risk of normoglycemic ketoacidosis, a condition where the body produces high levels of ketones even when blood sugar levels are normal. Finally, patients taking SGLT-2 inhibitors may be at increased risk for lower-limb amputations, so it is important to closely monitor the feet.
Despite these potential risks, SGLT-2 inhibitors can also have benefits. Patients taking these medications often experience weight loss, which can be beneficial for those with type 2 diabetes mellitus. Overall, it is important for patients to discuss the potential risks and benefits of SGLT-2 inhibitors with their healthcare provider before starting treatment.
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This question is part of the following fields:
- Endocrine System
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Question 19
Incorrect
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A woman in her 30s experiences dehydration from diarrhoea and vomiting, leading to activation of the renin-angiotensin-aldosterone system by her kidneys. This increases the pressure across the glomerulus and maintains glomerular filtration rate. What is the normal passage of blood through this area?
Your Answer: afferent arteriole- glomerular capillary bed- peritubular capillaries and medullary vasa recta- efferent arteriole
Correct Answer: afferent arteriole- glomerular capillary bed- efferent arteriole- peritubular capillaries and medullary vasa recta
Explanation:The journey of blood to a nephron begins with the afferent arteriole, followed by the glomerular capillary bed, efferent arteriole, and finally the peritubular capillaries and medullary vasa recta.
The afferent arteriole is the first stage, where blood enters the nephron. From there, it flows through the glomerulus and exits through the efferent arteriole.
If the efferent arteriole is constricted, it can increase pressure across the glomerulus, leading to a higher filtration fraction and maintaining eGFR.
The Loop of Henle and its Role in Renal Physiology
The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.
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This question is part of the following fields:
- Renal System
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Question 20
Incorrect
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A 32-year-old woman presents to the medical unit with fevers, rigors, and night sweats. She has been experiencing increased fatigue and nausea for the past 72 hours before developing fevers.
Upon examination, she appears lethargic and diaphoretic.
Initial vital signs are as follows:
Temperature 39ºC
Blood pressure 90/60 mmHg
Heart rate 120 beats per minute
Respiratory rate 22 breaths per minute
Oxygen saturations 97% on room air
The medical team initiates empirical antibiotic therapy and intravenous fluids while performing an infection screen and blood cultures.
After 48 hours, the patient's condition has improved. The provisional report from the blood cultures indicates the growth of gram-negative bacilli.
What is the most likely organism causing the patient's infection?Your Answer: Staphylococcus aureus
Correct Answer: Escherichia coli
Explanation:The patient is exhibiting symptoms of sepsis, but the source of the infection is unknown. Therefore, general measures for managing sepsis are necessary, including taking urine and blood cultures, providing blood pressure support, conducting screening investigations, and administering empirical antibiotic therapy.
It is important to have some knowledge of bacteria as blood culture results typically take 48 hours to become available and come with a provisional report. In this case, the provisional description fits with Escherichia coli, an aerobic gram-negative rod that is often associated with severe systemic features and corresponds to the patient’s initial presentation of Escherichia coli bacteraemia.
Other bacteria, such as Clostridium difficile, Pseudomonas aeruginosa, Streptococcus, and Staphylococcus species, do not match the description provided. Clostridium difficile is a gram-positive bacillus that causes healthcare-associated infections and colitis, while Pseudomonas aeruginosa is more commonly associated with infections in immunocompromised patients and medical devices. Streptococcus and Staphylococcus species are gram-positive cocci and do not correspond to the description given.
Classification of Bacteria Made Easy
Bacteria are classified based on their shape, staining properties, and other characteristics. One way to simplify the classification process is to remember that Gram-positive cocci include staphylococci and streptococci, while Gram-negative cocci include Neisseria meningitidis, Neisseria gonorrhoeae, and Moraxella catarrhalis. To categorize all bacteria, only a few Gram-positive rods or bacilli need to be memorized, which can be remembered using the mnemonic ABCD L: Actinomyces, Bacillus anthracis (anthrax), Clostridium, Diphtheria (Corynebacterium diphtheriae), and Listeria monocytogenes.
The remaining organisms are Gram-negative rods, such as Escherichia coli, Haemophilus influenzae, Pseudomonas aeruginosa, Salmonella sp., Shigella sp., and Campylobacter jejuni. By keeping these classifications in mind, it becomes easier to identify and differentiate between different types of bacteria.
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This question is part of the following fields:
- General Principles
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Question 21
Incorrect
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What is a primary function of vitamin A?
Your Answer: Immune response
Correct Answer: Vision
Explanation:Vitamin A: Forms, Sources, and Functions
Vitamin A is a crucial nutrient that exists in various forms in nature. The primary dietary form of vitamin A is retinol, also known as pre-formed vitamin A, which is stored in animal liver tissue as retinyl esters. The body can also produce its own vitamin A from carotenoids, with beta-carotene being the most common precursor molecule.
The richest sources of vitamin A include liver and fish liver oils, dark green leafy vegetables, carrots, and mangoes. Vitamin A can also be added to certain foods like cereals and margarines.
Vitamin A plays several essential roles in the body, including supporting vision by being a component of rhodopsin, a pigment required by the rod cells of the retina. It also contributes to the growth and development of various types of tissue, regulates gene transcription, and aids in the synthesis of hydrophobic glycoproteins and parts of the protein kinase enzyme pathways.
In summary, the different forms and sources of vitamin A and its vital functions in the body is crucial for maintaining optimal health.
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This question is part of the following fields:
- Basic Sciences
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Question 22
Incorrect
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A 2-day-old girl presents with sudden hypoxia, hypotension, and acidosis. Upon examination, pulses are found in the right upper limb but not in the left upper limb or legs. What congenital abnormality is the most likely cause of these symptoms?
Your Answer: Hypoplastic left heart syndrome
Correct Answer: Interruption of the aortic arch
Explanation:Circulatory collapse in newborns on day 1 is often caused by duct-dependent cardiac defects such as interruption of the aortic arch or left hypoplastic heart syndrome. These defects cause hypoxia, acidosis, and hypotension. Interruption of the aortic arch presents with upper limb pulses, while left hypoplastic heart syndrome presents with absent upper limb pulses. Anomalous pulmonary venous circulation and tetralogy of Fallot are not associated with early circulation collapse. Coarctation is a non-cyanotic defect that may be detected by weak femoral pulses, upper limb hypertension, or a pansystolic subclavicular/subscapular murmur.
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This question is part of the following fields:
- Paediatrics
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Question 23
Incorrect
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A 67-year-old male who has been newly diagnosed with giant cell arteritis presents with a positive relative afferent pupillary defect (RAPD) in his right eye during examination.
What is the significance of RAPD in this patient's diagnosis?Your Answer: The left and right eye appears to constrict when light is shone on the left eye
Correct Answer: The left and right eye appears to dilate when light is shone on the left eye
Explanation:When there is a relative afferent pupillary defect, shining light on the affected eye causes both the affected and normal eye to appear to dilate. This occurs because there are differences in the afferent pathway between the two eyes, often due to retinal or optic nerve disease, which results in reduced constriction of both pupils when light is directed from the unaffected eye to the affected eye.
A relative afferent pupillary defect, also known as the Marcus-Gunn pupil, can be identified through the swinging light test. This condition is caused by a lesion that is located anterior to the optic chiasm, which can be found in the optic nerve or retina. When light is shone on the affected eye, it appears to dilate while the normal eye remains unchanged.
The causes of a relative afferent pupillary defect can vary. For instance, it may be caused by a detachment of the retina or optic neuritis, which is often associated with multiple sclerosis. The pupillary light reflex pathway involves the afferent pathway, which starts from the retina and goes through the optic nerve, lateral geniculate body, and midbrain. The efferent pathway, on the other hand, starts from the Edinger-Westphal nucleus in the midbrain and goes through the oculomotor nerve.
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This question is part of the following fields:
- Neurological System
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Question 24
Correct
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A couple with a 1-year-old child are concerned about the possibility of their child having hypothyroidism, as they know someone whose child was recently diagnosed with the condition. They inquire about screening options, specifically mentioning the heel-prick test. Can you provide information on when this test is typically performed?
Your Answer: The heel-prick test is carried out on days 5-9 following birth
Explanation:The Guthrie test, performed 5-9 days after birth, screens for hypothyroidism and other disorders. The National Screening Committee recommends screening for congenital hypothyroidism, sickle cell disorders, cystic fibrosis, and six inherited metabolic diseases. Screening for congenital hypothyroidism involves checking for elevated TSH levels.
The Guthrie Test: Screening for Biochemical Disorders in Newborns
The Guthrie test, also known as the heel-prick test, is a screening procedure that is typically performed on newborns between 5 to 9 days after birth. This test is designed to detect the presence of several biochemical disorders that can cause serious health problems if left untreated.
The Guthrie test involves pricking the baby’s heel and collecting a small amount of blood on a special filter paper. The blood sample is then sent to a laboratory for analysis. The test screens for several disorders, including hypothyroidism, phenylketonuria, galactosaemia, maple syrup urine disease, and homocystinuria.
Hypothyroidism is a condition in which the thyroid gland does not produce enough hormones, which can lead to developmental delays and other health problems. Phenylketonuria is a genetic disorder that affects the body’s ability to break down an amino acid called phenylalanine, which can cause brain damage if left untreated. Galactosaemia is a rare genetic disorder that affects the body’s ability to process galactose, a sugar found in milk. Maple syrup urine disease is a metabolic disorder that prevents the body from breaking down certain amino acids, which can cause seizures and other serious health problems. Homocystinuria is a genetic disorder that affects the body’s ability to break down certain amino acids, which can cause developmental delays and other health problems.
Overall, the Guthrie test is an important screening tool that can help identify these and other biochemical disorders in newborns, allowing for early intervention and treatment to prevent serious health complications.
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This question is part of the following fields:
- General Principles
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Question 25
Correct
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A 30-year-old patient comes to you with symptoms of fever, thrush, malaise, and generalised lymphadenopathy. Your supervisor requests that you conduct an HIV blood test. What steps should you take?
Your Answer: Explain the implications for testing for HIV to the patient, seek permission and take the bloods yourself
Explanation:According to the GMC’s guidance on HIV & AIDS ethical considerations from October 1995 to October 1997, consent must be obtained for HIV testing due to the potential negative impact a diagnosis may have on an individual’s social and financial situation. Additionally, healthcare professionals are prohibited from refusing treatment to patients based on their medical condition, even if it poses a risk to the healthcare provider.
HIV seroconversion is a process where the body develops antibodies against the virus. This process is symptomatic in 60-80% of patients and usually presents as a glandular fever type illness. The severity of symptoms is associated with a poorer long-term prognosis. The symptoms typically occur 3-12 weeks after infection and include a sore throat, lymphadenopathy, malaise, myalgia, arthralgia, diarrhea, maculopapular rash, mouth ulcers, and rarely meningoencephalitis.
Diagnosing HIV involves testing for HIV antibodies, which may not be present in early infection. However, most people develop antibodies to HIV at 4-6 weeks, and 99% do so by 3 months. The diagnosis usually involves both a screening ELISA test and a confirmatory Western Blot Assay. Additionally, a p24 antigen test can be used to detect a viral core protein that appears early in the blood as the viral RNA levels rise. Combination tests that test for both HIV p24 antigen and HIV antibody are now standard for the diagnosis and screening of HIV. If the combined test is positive, it should be repeated to confirm the diagnosis. Some centers may also test the viral load (HIV RNA levels) if HIV is suspected at the same time. Testing for HIV in asymptomatic patients should be done at 4 weeks after possible exposure, and after an initial negative result, a repeat test should be offered at 12 weeks.
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This question is part of the following fields:
- General Principles
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Question 26
Correct
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A 32-year-old woman complains of faecal incontinence. She had a normal vaginal delivery 8 years ago. Which nerve injury is the most probable cause of her symptoms?
Your Answer: Pudendal
Explanation:The POOdendal nerve is responsible for keeping the poo up off the floor, and damage to this nerve is commonly linked to faecal incontinence. To address this issue, sacral neuromodulation is often used as a treatment. Additionally, constipation can be caused by injury to the hypogastric autonomic nerves.
The Pudendal Nerve and its Functions
The pudendal nerve is a nerve that originates from the S2, S3, and S4 nerve roots and exits the pelvis through the greater sciatic foramen. It then re-enters the perineum through the lesser sciatic foramen. This nerve provides innervation to the anal sphincters and external urethral sphincter, as well as cutaneous innervation to the perineum surrounding the anus and posterior vulva.
Late onset pudendal neuropathy may occur due to traction and compression of the pudendal nerve by the foetus during late pregnancy. This condition may contribute to the development of faecal incontinence. Understanding the functions of the pudendal nerve is important in diagnosing and treating conditions related to the perineum and surrounding areas.
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This question is part of the following fields:
- Neurological System
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Question 27
Incorrect
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A 75-year-old man is brought to his family doctor by his wife, who reports that her husband has been misplacing items around the house, such as putting his wallet in the fridge. She also mentions that he has gotten lost on two occasions while trying to find his way home. The man has difficulty remembering recent events but can recall his childhood and early adulthood with clarity. He denies experiencing any visual or auditory hallucinations or issues with his mobility. The wife notes that her husband's behavioral changes have been gradual rather than sudden. A CT scan reveals significant widening of the brain sulci. What is the most likely diagnosis for this man, and what is the underlying pathology?
Your Answer: Intracellular Lewy bodies
Correct Answer: Extracellular amyloid plaques and intracellular fibrillary tangles
Explanation:Alzheimer’s disease is caused by the deposition of insoluble beta-amyloid protein, leading to the formation of cortical plaques, and abnormal aggregation of the tau protein, resulting in intraneuronal neurofibrillary tangles. This disease is characterized by a gradual onset of memory and behavioral problems, as well as brain atrophy visible on CT scans. Vascular dementia, on the other hand, is caused by multiple ischemic insults to the brain, resulting in a stepwise decline in cognition. Prion disease, such as Creutzfeldt-Jakob disease, is characterized by the presence of insoluble beta-pleated protein sheets. Lacunar infarcts, caused by obstruction of small penetrating arteries in the brain, can be detected by MRI or CT scans. Lewy body dementia is characterized by the presence of intracellular Lewy bodies, along with symptoms of dementia and Parkinson’s disease.
Alzheimer’s disease is a type of dementia that gradually worsens over time and is caused by the degeneration of the brain. There are several risk factors associated with Alzheimer’s disease, including increasing age, family history, and certain genetic mutations. The disease is also more common in individuals of Caucasian ethnicity and those with Down’s syndrome.
The pathological changes associated with Alzheimer’s disease include widespread cerebral atrophy, particularly in the cortex and hippocampus. Microscopically, there are cortical plaques caused by the deposition of type A-Beta-amyloid protein and intraneuronal neurofibrillary tangles caused by abnormal aggregation of the tau protein. The hyperphosphorylation of the tau protein has been linked to Alzheimer’s disease. Additionally, there is a deficit of acetylcholine due to damage to an ascending forebrain projection.
Neurofibrillary tangles are a hallmark of Alzheimer’s disease and are partly made from a protein called tau. Tau is a protein that interacts with tubulin to stabilize microtubules and promote tubulin assembly into microtubules. In Alzheimer’s disease, tau proteins are excessively phosphorylated, impairing their function.
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This question is part of the following fields:
- Neurological System
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Question 28
Correct
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What is the organism that causes the majority of cases of epiglottitis in children who receive vaccinations in the UK?
Your Answer: Haemophilus influenzae type B
Explanation:Common Bacterial Infections in Children
Epiglottitis is a serious infection of the epiglottis that can be life-threatening. It is usually caused by Haemophilus influenzae type B (HiB) and is characterized by symptoms such as sepsis, stridor, and airway obstruction. Early and controlled intubation is crucial in managing this condition. Fortunately, the introduction of HiB vaccination in the UK has significantly reduced the incidence of epiglottitis, making it a rare condition.
Botulism is another bacterial infection that affects children. It is caused by the anaerobic C. botulinum, which produces a toxin that causes paralysis. Unlike HiB, there is no vaccine available for botulism.
Diphtheria, a severe pharyngitis that causes massive swelling of the neck, is now rare in the UK. The vaccination schedule includes C. diphtheriae, which is the bacteria that causes this condition.
Moraxella is a bacterial infection that causes respiratory tract and ear infections. Children are not vaccinated against it.
Staph. aureus is another bacterial infection that affects children. It causes cellulitis and wound infections, among others. However, there is no vaccine available for this condition.
In summary, while some bacterial infections such as epiglottitis and diphtheria have become rare in the UK due to vaccination, others such as botulism, Moraxella, and Staph. aureus still pose a risk to children. It is important to be aware of the symptoms and seek medical attention promptly if necessary.
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This question is part of the following fields:
- Microbiology
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Question 29
Correct
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Which one of the following nerves is the primary source of innervation to the anterior skin of the scrotum?
Your Answer: Ilioinguinal nerve
Explanation:The pudendal nerve innervates the posterior skin of the scrotum, while the ilioinguinal nerve primarily innervates the anterior scrotum. The genital branch of the genitofemoral nerve also provides some innervation.
Scrotal Sensation and Nerve Innervation
The scrotum is a sensitive area of the male body that is innervated by two main nerves: the ilioinguinal nerve and the pudendal nerve. The ilioinguinal nerve originates from the first lumbar vertebrae and passes through the internal oblique muscle before reaching the superficial inguinal ring. From there, it provides sensation to the anterior skin of the scrotum.
The pudendal nerve, on the other hand, is the primary nerve of the perineum. It arises from three nerve roots in the pelvis and passes through the greater and lesser sciatic foramina to enter the perineal region. Its perineal branches then divide into posterior scrotal branches, which supply the skin and fascia of the perineum. The pudendal nerve also communicates with the inferior rectal nerve.
Overall, the innervation of the scrotum is complex and involves multiple nerves. However, understanding the anatomy and function of these nerves is important for maintaining proper scrotal sensation and overall male health.
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This question is part of the following fields:
- Neurological System
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Question 30
Incorrect
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A young woman comes in with a sudden and severe headache at the back of her head, which quickly leads to seizures. Upon examination, doctors discover an aneurysm. During the assessment, they observe that her right eye is displaced downwards and to the side. What could be the probable reason for this?
Your Answer: Abducens nerve palsy
Correct Answer: Oculomotor nerve palsy
Explanation:When someone has oculomotor nerve palsy, their medial rectus muscle is disabled, which causes the lateral rectus muscle to move the eye uncontrollably to the side. Additionally, the superior rectus, inferior rectus, and inferior oblique muscles are also affected, causing the eye to move downwards due to the unopposed action of the superior oblique muscle. This condition also results in ptosis, or drooping of the eyelid, due to paralysis of the levator palpebrae superioris muscle, and mydriasis, or dilation of the pupil, due to damage to the parasympathetic fibers.
Disorders of the Oculomotor System: Nerve Path and Palsy Features
The oculomotor system is responsible for controlling eye movements and pupil size. Disorders of this system can result in various nerve path and palsy features. The oculomotor nerve has a large nucleus at the midbrain and its fibers pass through the red nucleus and the pyramidal tract, as well as through the cavernous sinus into the orbit. When this nerve is affected, patients may experience ptosis, eye down and out, and an inability to move the eye superiorly, inferiorly, or medially. The pupil may also become fixed and dilated.
The trochlear nerve has the longest intracranial course and is the only nerve to exit the dorsal aspect of the brainstem. Its nucleus is located at the midbrain and it passes between the posterior cerebral and superior cerebellar arteries, as well as through the cavernous sinus into the orbit. When this nerve is affected, patients may experience vertical diplopia (diplopia on descending the stairs) and an inability to look down and in.
The abducens nerve has its nucleus in the mid pons and is responsible for the convergence of eyes in primary position. When this nerve is affected, patients may experience lateral diplopia towards the side of the lesion and the eye may deviate medially. Understanding the nerve path and palsy features of the oculomotor system can aid in the diagnosis and treatment of disorders affecting this important system.
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This question is part of the following fields:
- Neurological System
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Question 31
Incorrect
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A 60-year-old patient visits the GP with symptoms indicative of a rotator cuff injury. The GP intends to assess the subscapularis muscle. What is the most suitable special test to examine the subscapularis muscle?
Your Answer: Empty can test
Correct Answer: Lift-off test
Explanation:If a lift-off test shows abnormal results, it suggests that the subscapularis muscle may be involved.
Rotator cuff injuries are a common cause of shoulder problems and can be classified into four types of disease: subacromial impingement, calcific tendonitis, rotator cuff tears, and rotator cuff arthropathy. The symptoms of a rotator cuff injury include shoulder pain that worsens during abduction. The signs of a rotator cuff injury include tenderness over the anterior acromion and a painful arc of abduction. The painful arc of abduction is typically between 60 and 120 degrees for subacromial impingement, while for rotator cuff tears, the pain may be in the first 60 degrees. Proper diagnosis and treatment are essential to prevent further damage and improve shoulder function.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 32
Correct
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What is the most accurate definition of evidence-based medicine (EBM)?
Your Answer: EBM is the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients
Explanation:Evidence-Based Medicine
Evidence-based medicine (EBM) is a widely accepted approach to healthcare decision-making that involves the conscientious, explicit, and judicious use of current best evidence. This approach integrates the best available evidence with individual patient preferences to make informed decisions about patient care. While economic analyses can help allocate resources in a cost-effective manner, critical appraisal of clinical research is also an essential element of EBM.
EBM recognizes that high-quality randomized controlled trials and systematic reviews are valuable sources of evidence, but they are not the only sources. Practicing according to guidelines can be beneficial if the guidelines are evidence-based, but this is not always the case. Ultimately, the goal of EBM is to provide patients with the best possible care by using the most current and reliable evidence available while taking into account individual patient preferences and characteristics. By doing so, healthcare providers can make informed decisions that lead to better patient outcomes.
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This question is part of the following fields:
- Clinical Sciences
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Question 33
Incorrect
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A 40-year-old teacher has come to your office seeking information about a new cancer treatment. She was recently diagnosed with melanoma and her oncologist has recommended treatment with an immune checkpoint inhibitor called Pembrolizumab (Keytruda).
She is curious about how this class of drugs works to treat cancer.
Could you explain the mechanism of action of immune checkpoint inhibitors to her?
Thank you.Your Answer: They work by reactivating and increasing the body’s own natural killer cell population
Correct Answer: They work by reactivating and increasing the body’s own T-cell population
Explanation:To treat solid tumours, immune checkpoint inhibitors are becoming a popular substitute for cytotoxic chemotherapy. These inhibitors function by reactivating and boosting the body’s T-cell population. While radiotherapy harms cancer cell DNA, chemotherapy directly impacts the growth and multiplication of cancer cells.
Understanding Immune Checkpoint Inhibitors
Immune checkpoint inhibitors are a type of immunotherapy that is becoming increasingly popular in the treatment of certain types of cancer. Unlike traditional therapies such as chemotherapy, these targeted treatments work by harnessing the body’s natural anti-cancer immune response. They boost the immune system’s ability to attack and destroy cancer cells, rather than directly affecting their growth and proliferation.
T-cells are an essential part of our immune system that helps destroy cancer cells. However, some cancer cells produce high levels of proteins that turn T-cells off. Checkpoint inhibitors block this process and reactivate and increase the body’s T-cell population, enhancing the immune system’s ability to recognize and fight cancer cells.
There are different types of immune checkpoint inhibitors, including Ipilimumab, Nivolumab, Pembrolizumab, Atezolizumab, Avelumab, and Durvalumab. These drugs block specific proteins found on T-cells and cancer cells, such as CTLA-4, PD-1, and PD-L1. They are administered by injection or intravenous infusion and can be given as a single-agent treatment or combined with chemotherapy or each other.
However, the mechanism of action of these drugs can result in side effects termed ‘Immune-related adverse events’ that are inflammatory and autoimmune in nature. This is because all immune cells are boosted by these drugs, not just the ones that target cancer. The overactive T-cells can produce side effects such as dry, itchy skin and rashes, nausea and vomiting, decreased appetite, diarrhea, tiredness and fatigue, shortness of breath, and a dry cough. Management of such side effects reflects the inflammatory nature, often involving corticosteroids. It is important to monitor liver, kidney, and thyroid function as these drugs can affect these organs.
In conclusion, the early success of immune checkpoint inhibitors in solid tumors has generated tremendous interest in further developing and exploring these strategies across the oncology disease spectrum. Ongoing testing in clinical trials creates new hope for patients affected by other types of disease.
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This question is part of the following fields:
- Haematology And Oncology
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Question 34
Correct
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You perform venepuncture on the basilic vein in the cubital fossa.
At which point does this vein pass deep under muscle?Your Answer: Midway up the humerus
Explanation:When the basilic vein is located halfway up the humerus, it travels beneath muscle. At the cubital fossa, the basilic vein connects with the median cubital vein, which in turn interacts with the cephalic vein. Contrary to popular belief, the basilic vein does not pass through the medial epicondyle. Meanwhile, the cephalic vein can be found in the deltopectoral groove.
The Basilic Vein: A Major Pathway of Venous Drainage for the Arm and Hand
The basilic vein is one of the two main pathways of venous drainage for the arm and hand, alongside the cephalic vein. It begins on the medial side of the dorsal venous network of the hand and travels up the forearm and arm. Most of its course is superficial, but it passes deep under the muscles midway up the humerus. Near the region anterior to the cubital fossa, the basilic vein joins the cephalic vein.
At the lower border of the teres major muscle, the anterior and posterior circumflex humeral veins feed into the basilic vein. It is often joined by the medial brachial vein before draining into the axillary vein. The basilic vein is continuous with the palmar venous arch distally and the axillary vein proximally. Understanding the path and function of the basilic vein is important for medical professionals in diagnosing and treating conditions related to venous drainage in the arm and hand.
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This question is part of the following fields:
- Cardiovascular System
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Question 35
Correct
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Which of the following is true regarding rheumatoid factor?
Your Answer: It is usually an IgM molecule reacting against patient's own IgG
Explanation:IgM antibody against IgG is known as rheumatoid factor.
Rheumatoid arthritis is a condition that requires initial investigations to determine the presence of antibodies. One such antibody is rheumatoid factor (RF), which is usually an IgM antibody that reacts with the patient’s own IgG. The Rose-Waaler test or latex agglutination test can detect RF, with the former being more specific. RF is positive in 70-80% of patients with rheumatoid arthritis, and high levels are associated with severe progressive disease. However, it is not a marker of disease activity. Other conditions that may have a positive RF include Felty’s syndrome, Sjogren’s syndrome, infective endocarditis, SLE, systemic sclerosis, and the general population. Anti-cyclic citrullinated peptide antibody is another antibody that may be detectable up to 10 years before the development of rheumatoid arthritis. It has a sensitivity similar to RF but a much higher specificity of 90-95%. NICE recommends testing for anti-CCP antibodies in patients with suspected rheumatoid arthritis who are RF negative. Additionally, x-rays of the hands and feet are recommended for all patients with suspected rheumatoid arthritis.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 36
Incorrect
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Jill, a 54-year-old female, visits her doctor complaining of chest pain. She reports that the pain worsens when she walks and subsides when she rests.
Jill's medical history includes diabetes, hypercholesterolemia, and hypertension. She also has a family history of myocardial infarction.
Based on her symptoms, the doctor diagnoses Jill with angina and prescribes a nitrate spray.
At what stage of the cardiac cycle do the coronary arteries primarily fill?Your Answer: Atrial diastole
Correct Answer: Ventricular diastole
Explanation:The filling of the coronary arteries takes place during ventricular diastole and not during ventricular systole, which is when isovolumetric contraction occurs.
Understanding Coronary Circulation
Coronary circulation refers to the blood flow that supplies the heart with oxygen and nutrients. The arterial supply of the heart is divided into two main branches: the left coronary artery (LCA) and the right coronary artery (RCA). The LCA originates from the left aortic sinus, while the RCA originates from the right aortic sinus. The LCA further divides into two branches, the left anterior descending (LAD) and the circumflex artery, while the RCA supplies the posterior descending artery.
The LCA supplies the left ventricle, left atrium, and interventricular septum, while the RCA supplies the right ventricle and the inferior wall of the left ventricle. The SA node, which is responsible for initiating the heartbeat, is supplied by the RCA in 60% of individuals, while the AV node, which is responsible for regulating the heartbeat, is supplied by the RCA in 90% of individuals.
On the other hand, the venous drainage of the heart is through the coronary sinus, which drains into the right atrium. During diastole, the coronary arteries fill with blood, allowing for the delivery of oxygen and nutrients to the heart muscles. Understanding the coronary circulation is crucial in the diagnosis and management of various heart diseases.
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This question is part of the following fields:
- Cardiovascular System
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Question 37
Incorrect
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You plan to conduct a study to determine if three different diets, each with varying sugar content, have varying effects on weight gain in individuals of different ages. Which statistical test would you use to show a significant difference between the diets?
Your Answer: Chi squared test
Correct Answer: ANOVA
Explanation:Understanding ANOVA: A Statistical Test for Comparing Multiple Group Means
ANOVA is a statistical test used to determine if there are significant differences between the means of multiple groups. Unlike the t-test, which only compares two means, ANOVA can compare more than two means. However, ANOVA assumes that the variable being tested is normally distributed. If this assumption is not met, nonparametric tests such as the Kruskal-Wallis analysis of ranks, the Median test, Friedman’s two-way analysis of variance, and Cochran Q test can be used instead.
The ANOVA test works by comparing the variance of the means. It distinguishes between within-group variance, which is the variance of the sample mean, and between-group variance, which is the variance between the separate sample means. The null hypothesis assumes that the variance of all the means is the same, and that within-group variance is the same as between-group variance. The test is based on the ratio of these two variances, which is known as the F statistic.
In summary, ANOVA is a useful statistical test for comparing multiple group means. However, it is important to ensure that the variable being tested is normally distributed. If this assumption is not met, nonparametric tests can be used instead.
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This question is part of the following fields:
- General Principles
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Question 38
Incorrect
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A senior citizen presents to the emergency department with recent onset of vision loss. A stroke is suspected, and an MRI is conducted. The scan reveals an acute ischemic infarct in the thalamus.
Which specific nucleus of the thalamus has been impacted by this infarct?Your Answer: Ventro-posterior lateral nucleus
Correct Answer: Lateral geniculate nucleus
Explanation:Visual impairment can occur when there is damage to the lateral geniculate nucleus, which is responsible for carrying visual information from the optic tracts to the occipital lobe via the optic radiations. This can result in a loss of vision in the contralateral visual field, often with preservation of central vision. The medial geniculate nucleus is responsible for processing auditory information, while the ventral anterior nucleus and ventro-posterior medial and lateral nuclei relay information related to motor function and somatosensation, respectively.
The Thalamus: Relay Station for Motor and Sensory Signals
The thalamus is a structure located between the midbrain and cerebral cortex that serves as a relay station for motor and sensory signals. Its main function is to transmit these signals to the cerebral cortex, which is responsible for processing and interpreting them. The thalamus is composed of different nuclei, each with a specific function. The lateral geniculate nucleus relays visual signals, while the medial geniculate nucleus transmits auditory signals. The medial portion of the ventral posterior nucleus (VML) is responsible for facial sensation, while the ventral anterior/lateral nuclei relay motor signals. Finally, the lateral portion of the ventral posterior nucleus is responsible for body sensation, including touch, pain, proprioception, pressure, and vibration. Overall, the thalamus plays a crucial role in the transmission of sensory and motor information to the brain, allowing us to perceive and interact with the world around us.
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This question is part of the following fields:
- Neurological System
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Question 39
Correct
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As a GP, you are approached by a 16-year-old girl named Lily who has a family history of breast cancer and is concerned about her own risk. Her mother carries the BRCA1 gene and has undergone a prophylactic mastectomy. Lily is requesting to be tested for the gene, but you have never encountered a case where a patient under 18 years has requested BRCA1 genetic testing before. You are unsure about the appropriateness of offering the test to someone so young, but Lily and her mother are insistent. What is the next best course of action?
Your Answer: Discuss the pros and cons of testing and implications for treatment with both Chloe and her mother. If you decide that she is competent to decide about testing then provide written information and additional materials to help them consider the matter further. Advise them that you would like further advice from the genetics and breast teams before you all make a final decision about whether to test.
Explanation:Balancing Autonomy and Medical Professionalism in Genetic Testing
In cases where a patient requests genetic testing, medical professionals must balance the patient’s autonomy with their own duty to act in the patient’s best interests. This is particularly important when dealing with minors, as they may not fully understand the implications of a positive test result. In such cases, it is important to consider the psychological impact of testing and whether it is appropriate to provide the test at this time.
As a medical professional, it is important to take the patient’s request seriously and not dismiss it or leave it to others to decide. However, it is also important to assess the patient’s capacity to make decisions and to consider whether testing is truly in their best interests. If necessary, seeking expert help in counseling the patient and their family can be beneficial.
Ultimately, medical professionals must balance the patient’s autonomy with their own duty to act in the patient’s best interests. This may mean declining to provide a test if it is not appropriate or if the patient lacks the capacity to fully understand the implications of a positive result. By carefully considering these factors, medical professionals can ensure that they are providing the best possible care to their patients.
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This question is part of the following fields:
- Ethics And Law
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Question 40
Correct
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An anaesthetist trainee administers neostigmine to a 60-year-old patient at the end of a brief surgical procedure to reverse the effect of a muscle relaxant. However, no effect is observed. Which of the following skeletal muscle relaxants may have been used during induction of anaesthesia?
Your Answer: Suxamethonium
Explanation:Suxamethonium is a type of skeletal muscle relaxant that causes depolarization. Unlike non-depolarizing agents such as tubocurarine, pancuronium, vecuronium, and rocuronium, it cannot be reversed by anticholinesterases because it is broken down by butyrylcholinesterase. Neostigmine, an anticholinesterase, prolongs the effects of acetylcholine by inhibiting acetylcholinesterase in the synaptic cleft, but it cannot reverse the effects of suxamethonium since it is not metabolized by acetylcholinesterase.
Cholinergic receptors are proteins found in the body that are activated by the neurotransmitter acetylcholine. They are present in both the central and peripheral nervous systems and can be divided into two groups: nicotinic and muscarinic receptors. Nicotinic receptors are ligand-gated ion channels that allow the movement of sodium into the cell and potassium out, resulting in an inward flow of positive ions. Muscarinic receptors, on the other hand, are G-protein coupled receptors that exert their downstream effect by linking with different G-proteins.
Nicotinic receptors are named after their binding capacity for nicotine, but they respond to acetylcholine. They are found in preganglionic neurons of the autonomic nervous system and at neuromuscular junctions. At preganglionic neurons, they create a local membrane depolarization through the movement of sodium into the cell, while at neuromuscular junctions, they initiate a wave of depolarization across the muscle cell. Muscarinic receptors are found in effector organs of the parasympathetic autonomic nervous system and are divided into five classes. They mediate various effects through different G-protein systems.
Cholinergic receptors can be targeted pharmacologically using agonists and antagonists. For example, muscarinic antagonist ipratropium can be used to induce bronchodilation in asthma or chronic obstructive pulmonary disease. In myasthenia gravis, an autoimmune disease, antibodies are directed against the nicotinic receptor on the neuromuscular junction, resulting in skeletal muscle weakness. Understanding the effects associated with each type of cholinergic receptor is important in understanding physiological responses to drugs and disease.
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This question is part of the following fields:
- General Principles
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